Hack is a roguelike video game inspired by Rogue that introduced shops as gameplay elements and expanded available monsters, items, and spells. The game uses arrangements of ASCII or Extended ASCII glyphs to represent game elements.

Hack was created in 1982 by Jay Fenlason with the assistance of Kenny Woodland, Mike Thome, and Jonathan Payne, while students at Lincoln-Sudbury Regional High School. A greatly extended version was posted on Usenet in 1984 by Andries Brouwer. It is licensed under a 3-clause BSD-like license.

The object of the game is to delve into a dungeon to retrieve the Amulet of Yendor. The player confronts various monsters: hobgoblins, leprechauns, acid blobs, bats, centaurs, chameleons, dragons, ghosts, imps, trolls, and more. The player must have a fire-resistance ring on to enter Hell, and taking it off while there causes instant death. (In later versions, Hell is renamed and having fire-resistance is no longer necessary.) The player encounters special rooms such as shops, crypts, and vaults. Also found in the game are traps, food items, weapons, tools, armor, potions, scrolls, wands, gems and rings.